{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T20:32:01Z","timestamp":1788899521322,"version":"build-2803163510"},"reference-count":43,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2025,1,28]],"date-time":"2025-01-28T00:00:00Z","timestamp":1738022400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"University of California, Berkeley"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background: Human cytomegalovirus (CMV) is the most common cause of viral congenital infections worldwide. The development of effective vaccines against human CMV infection and disease is a high priority. Attenuated Salmonella are attractive oral vaccine vectors against human diseases because they can be administrated orally. Methods: In this study, an attenuated Salmonella strain was generated as an oral vaccine vector for the delivery and expression of the M78 protein of murine cytomegalovirus (MCMV). Using the MCMV infection of mice as the CMV infection model, we characterized the immune responses and protection induced by the constructed Salmonella-based vaccine. Results: The generated Salmonella-based vaccine, v-M78, which contained an M78 expression plasmid construct, carried out gene transfer efficiently for M78 expression and showed little pathogenicity and virulence in mice. In orally vaccinated mice, v-M78 induced anti-MCMV serum IgG and mucosal IgA responses and also elicited anti-MCMV T cell responses. Furthermore, mice immunized with v-M78 were protected from intraperitoneal and intranasal challenges with MCMV. The v-M78 vaccination reduced the titers of the challenged viruses in spleens, livers, lungs, and salivary glands. Conclusions: These results provide the first direct evidence that a Salmonella-based vaccine expressing M78 elicits strong humoral and cellular immune responses and induces immune protection against MCMV infection. Furthermore, our study demonstrates the potential of using Salmonella-based oral vaccines against CMV infection.<\/jats:p>","DOI":"10.3390\/vaccines13020137","type":"journal-article","created":{"date-parts":[[2025,1,28]],"date-time":"2025-01-28T06:47:29Z","timestamp":1738046849000},"page":"137","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Effective Immune Protection of Mice from Murine Cytomegalovirus Infection by Oral Salmonella-Based Vaccine Expressing Viral M78 Antigen"],"prefix":"10.3390","volume":"13","author":[{"given":"Yujun","family":"Liu","sequence":"first","affiliation":[{"name":"School of Public Health, University of California, Berkeley, CA 94720, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hao","family":"Gong","sequence":"additional","affiliation":[{"name":"School of Public Health, University of California, Berkeley, CA 94720, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiaming","family":"Zhu","sequence":"additional","affiliation":[{"name":"School of Public Health, University of California, Berkeley, CA 94720, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fenyong","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Public Health, University of California, Berkeley, CA 94720, USA"},{"name":"Program in Comparative Biochemistry, University of California, Berkeley, CA 94720, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,1,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1008","DOI":"10.1001\/jama.289.8.1008","article-title":"Maternal immunity and prevention of congenital cytomegalovirus infection","volume":"289","author":"Fowler","year":"2003","journal-title":"JAMA"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"e2120736","DOI":"10.1001\/jamanetworkopen.2021.20736","article-title":"Congenital Cytomegalovirus Infection Burden and Epidemiologic Risk Factors in Countries With Universal Screening: A Systematic Review and Meta-analysis","volume":"4","author":"Ssentongo","year":"2021","journal-title":"JAMA Netw. Open"},{"key":"ref_3","first-page":"389","article-title":"Cytomegalovirus","volume":"Volume 1","author":"Knipe","year":"2021","journal-title":"Fields Virology: DNA Viruses"},{"key":"ref_4","first-page":"212","article-title":"The Family Herpesviridae: A Brief Introduction","volume":"Volume 1","author":"Knipe","year":"2021","journal-title":"Fields Virology: DNA Viruses"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1366","DOI":"10.1056\/NEJM200105033441804","article-title":"Intrauterine transmission of cytomegalovirus to infants of women with preconceptional immunity","volume":"344","author":"Boppana","year":"2001","journal-title":"N. Engl. J. Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"e42","DOI":"10.1111\/1471-0528.17966","article-title":"Congenital Cytomegalovirus Infection: Update on Screening, Diagnosis and Treatment: Scientific Impact Paper No. 56","volume":"132","author":"Khalil","year":"2025","journal-title":"BJOG"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"S113","DOI":"10.1093\/infdis\/jiz447","article-title":"The Status of Vaccine Development Against the Human Cytomegalovirus","volume":"221","author":"Plotkin","year":"2020","journal-title":"J. Infect. Dis."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Bruce, K., Ma, J., Lawler, C., Xie, W., Stevenson, P.G., and Farrell, H.E. (2022). Recent Advancements in Understanding Primary Cytomegalovirus Infection in a Mouse Model. Viruses, 14.","DOI":"10.3390\/v14091934"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e0126421","DOI":"10.1128\/JVI.01264-21","article-title":"A Live Olfactory Mouse Cytomegalovirus Vaccine, Attenuated for Systemic Spread, Protects against Superinfection","volume":"95","author":"Farrell","year":"2021","journal-title":"J. Virol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1186\/1743-422X-11-104","article-title":"Comparison of multiple DNA vaccines for protection against cytomegalovirus infection in BALB\/c mice","volume":"11","author":"Huang","year":"2014","journal-title":"Virol. J."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"3696","DOI":"10.1128\/JVI.74.8.3696-3708.2000","article-title":"Suppression of murine cytomegalovirus (MCMV) replication with a DNA vaccine encoding MCMV M84 (a homolog of human cytomegalovirus pp65)","volume":"74","author":"Morello","year":"2000","journal-title":"J. Virol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1128\/JVI.79.1.159-175.2005","article-title":"Systemic priming-boosting immunization with a trivalent plasmid DNA and inactivated murine cytomegalovirus (MCMV) vaccine provides long-term protection against viral replication following systemic or mucosal MCMV challenge","volume":"79","author":"Morello","year":"2005","journal-title":"J. Virol."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Wang, H., Huang, C., Dong, J., Yao, Y., Xie, Z., Liu, X., Zhang, W., Fang, F., and Chen, Z. (2015). Complete protection of mice against lethal murine cytomegalovirus challenge by immunization with DNA vaccines encoding envelope glycoprotein complex III antigens gH, gL and gO. PLoS ONE, 10.","DOI":"10.1371\/journal.pone.0119964"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"328","DOI":"10.1128\/CMR.5.3.328","article-title":"Oral immunization using live attenuated Salmonella spp. as carriers of foreign antigens","volume":"5","author":"Cardenas","year":"1992","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1016\/j.ijmm.2007.08.006","article-title":"Rational design of Salmonella recombinant vaccines","volume":"298","author":"Cheminay","year":"2008","journal-title":"Int. J. Med. Microbiol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"39","DOI":"10.4049\/jimmunol.1600608","article-title":"Salmonella Vaccines: Conduits for Protective Antigens","volume":"200","author":"Curtiss","year":"2018","journal-title":"J. Immunol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"13070","DOI":"10.1073\/pnas.1201620109","article-title":"Effective inhibition of cytomegalovirus infection by external guide sequences in mice","volume":"109","author":"Jiang","year":"2012","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1111\/j.1574-6968.2006.00470.x","article-title":"Differential effect of auxotrophies on the release of macromolecules by Salmonella enterica vaccine strains","volume":"265","author":"Loessner","year":"2006","journal-title":"FEMS Microbiol. Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"728","DOI":"10.1111\/j.1462-5822.2006.00706.x","article-title":"Manipulating cellular transport and immune responses: Dynamic interactions between intracellular Salmonella enterica and its host cells","volume":"8","author":"Abrahams","year":"2006","journal-title":"Cell Microbiol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"501","DOI":"10.1046\/j.1462-5822.2003.00294.x","article-title":"Functions and effectors of the Salmonella pathogenicity island 2 type III secretion system","volume":"5","author":"Waterman","year":"2003","journal-title":"Cell. Microbiol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"19414","DOI":"10.1073\/pnas.1217554109","article-title":"Turning self-destructing Salmonella into a universal DNA vaccine delivery platform","volume":"109","author":"Kong","year":"2012","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1111\/j.1365-2958.2005.04668.x","article-title":"The PhoP\/PhoQ system controls the intramacrophage type three secretion system of Salmonella enterica","volume":"57","author":"Bijlsma","year":"2005","journal-title":"Mol. Microbiol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"329","DOI":"10.1146\/annurev-virology-100220-113942","article-title":"Viral G Protein-Coupled Receptors Encoded by beta- and gamma-Herpesviruses","volume":"9","author":"Rosenkilde","year":"2022","journal-title":"Annu. Rev. Virol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"3237","DOI":"10.1073\/pnas.051629898","article-title":"Murine cytomegalovirus M78 protein, a G protein-coupled receptor homologue, is a constituent of the virion and facilitates accumulation of immediate-early viral mRNA","volume":"98","author":"Oliveira","year":"2001","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Yunis, J., Farrell, H.E., Bruce, K., Lawler, C., Sidenius, S., Wyer, O., Davis-Poynter, N., and Stevenson, P.G. (2018). Murine cytomegalovirus degrades MHC class II to colonize the salivary glands. PLoS Pathog., 14.","DOI":"10.1371\/journal.ppat.1006905"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"6891","DOI":"10.1128\/JVI.78.13.6891-6899.2004","article-title":"Murine cytomegalovirus with a transposon insertional mutation at open reading frame m155 is deficient in growth and virulence in mice","volume":"78","author":"Abenes","year":"2004","journal-title":"J. Virol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"9488","DOI":"10.1128\/JVI.74.20.9488-9497.2000","article-title":"In vitro and in vivo characterization of a murine cytomegalovirus with a transposon insertional mutation at open reading frame M43","volume":"74","author":"Xiao","year":"2000","journal-title":"J. Virol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"8833","DOI":"10.1128\/jvi.70.12.8833-8849.1996","article-title":"Analysis of the complete DNA sequence of murine cytomegalovirus","volume":"70","author":"Rawlinson","year":"1996","journal-title":"J. Virol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"14223","DOI":"10.1073\/pnas.2334032100","article-title":"Functional profiling of human cytomegalovirus genome","volume":"100","author":"Dunn","year":"2003","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"7056","DOI":"10.1128\/JVI.73.8.7056-7060.1999","article-title":"Systematic excision of vector sequences from the BAC-cloned herpesvirus genome during virus reconstitution","volume":"73","author":"Wagner","year":"1999","journal-title":"J. Virol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1099\/vir.0.004853-0","article-title":"Analysis of the subcellular trafficking properties of murine cytomegalovirus M78, a 7 transmembrane receptor homologue","volume":"90","author":"Sharp","year":"2009","journal-title":"J. Gen. Virol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"6640","DOI":"10.1073\/pnas.120163297","article-title":"One-step inactivation of chromosomal genes in Escherichia coli K-12 using PCR products","volume":"97","author":"Datsenko","year":"2000","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"238","DOI":"10.1038\/291238a0","article-title":"Aromatic-dependent Salmonella typhimurium are non-virulent and effective as live vaccines","volume":"291","author":"Hoiseth","year":"1981","journal-title":"Nature"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Gong, H., Vu, G., Bai, Y., Chan, E., Wu, R., Yang, E., Liu, F., and Lu, S. (2011). A Salmonella small non-coding RNA facilitates bacterial invasion and intracellular replication by modulating the expression of virulence factors. PLoS Pathog., 7.","DOI":"10.1371\/journal.ppat.1002120"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1128\/IAI.70.2.451-461.2002","article-title":"The global regulator ArcA controls resistance to reactive nitrogen and oxygen intermediates in Salmonella enterica serovar Enteritidis","volume":"70","author":"Lu","year":"2002","journal-title":"Infect. Immun."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"6832","DOI":"10.1128\/JVI.00609-11","article-title":"A reassortment-incompetent live attenuated influenza virus vaccine for protection against pandemic virus strains","volume":"85","author":"Hai","year":"2011","journal-title":"J. Virol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"e0032022","DOI":"10.1128\/jvi.00320-22","article-title":"Reduction of Influenza A Virus Transmission in Mice by a Universal Intranasal Vaccine Candidate is Long-Lasting and Does Not Require Antibodies","volume":"96","author":"Price","year":"2022","journal-title":"J. Virol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"6019","DOI":"10.1128\/JVI.03101-13","article-title":"Mucosal immunization with a candidate universal influenza vaccine reduces virus transmission in a mouse model","volume":"88","author":"Price","year":"2014","journal-title":"J. Virol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"2561","DOI":"10.1016\/j.vaccine.2011.01.060","article-title":"The virus-induced signaling adaptor molecule enhances DNA-raised immune protection against H5N1 influenza virus infection in mice","volume":"29","author":"Luo","year":"2011","journal-title":"Vaccine"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"7269","DOI":"10.1073\/pnas.0912813107","article-title":"Salmonella-mediated delivery of RNase P ribozymes for inhibition of viral gene expression and replication in human cells","volume":"107","author":"Bai","year":"2010","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"477","DOI":"10.1111\/j.1365-2958.2007.05800.x","article-title":"The response regulator SsrB activates expression of diverse Salmonella pathogenicity island 2 promoters and counters silencing by the nucleoid-associated protein H-NS","volume":"65","author":"Walthers","year":"2007","journal-title":"Mol. Microbiol."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1996","DOI":"10.1086\/315497","article-title":"Biodistribution and genetic stability of the novel antitumor agent VNP20009, a genetically modified strain of Salmonella typhimurium","volume":"181","author":"Clairmont","year":"2000","journal-title":"J. Infect. Dis."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"888","DOI":"10.1172\/JCI112899","article-title":"Safety, infectivity, immunogenicity, and in vivo stability of two attenuated auxotrophic mutant strains of Salmonella typhi, 541Ty and 543Ty, as live oral vaccines in humans","volume":"79","author":"Levine","year":"1987","journal-title":"J. Clin. Investig."}],"container-title":["Vaccines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-393X\/13\/2\/137\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,8]],"date-time":"2025-10-08T10:37:47Z","timestamp":1759919867000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-393X\/13\/2\/137"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,1,28]]},"references-count":43,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2025,2]]}},"alternative-id":["vaccines13020137"],"URL":"https:\/\/doi.org\/10.3390\/vaccines13020137","relation":{},"ISSN":["2076-393X"],"issn-type":[{"value":"2076-393X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,1,28]]}}}